refactor: remove error_descriptor_class and NonStaffErrorBlock

It's safe to remove this because non-staff [1] users cannot access [2]
an `ErrorBlock`. We were able to reproduce this with and without this commit
with the following results:
1. Staff users were seeing the `ErrorBlock`.
2. Non-staff users were getting an empty `<div class="vert-mod"></div>`.

In theory, error blocks should be hidden in the Learning MFE because of this
option [3]. However, when we manually set `hide_access_error_blocks` to
`False`, we kept getting identical results (with and without this commit), so
it looks that the removal `NonStaffErrorBlock` was just omitted at some point.

[1] a4ec4c1b8e/lms/djangoapps/courseware/access.py (L419-L436)
[2] a4ec4c1b8e/lms/djangoapps/courseware/access.py (L150-L151)
[3] 92ca176fde/lms/djangoapps/courseware/views/views.py (L1547-L1551)

cms/djangoapps/contentstore/views/preview.py

@@ -17,7 +17,6 @@ from xblock.exceptions import NoSuchHandlerError
 from xblock.runtime import KvsFieldData
 
 from xmodule.contentstore.django import contentstore
-from xmodule.error_module import ErrorBlock
 from xmodule.exceptions import NotFoundError, ProcessingError
 from xmodule.modulestore.django import ModuleI18nService, modulestore
 from xmodule.partitions.partitions_service import PartitionService
@@ -218,7 +217,6 @@ def _preview_module_system(request, descriptor, field_data):
         # Set up functions to modify the fragment produced by student_view
         wrappers=wrappers,
         wrappers_asides=wrappers_asides,
-        error_descriptor_class=ErrorBlock,
         # Get the raw DescriptorSystem, not the CombinedSystem
         descriptor_runtime=descriptor._runtime,  # pylint: disable=protected-access
         services={

lms/djangoapps/courseware/module_render.py

@@ -40,7 +40,6 @@ from xblock.reference.plugins import FSService
 from xblock.runtime import KvsFieldData
 
 from xmodule.contentstore.django import contentstore
-from xmodule.error_module import ErrorBlock, NonStaffErrorBlock
 from xmodule.exceptions import NotFoundError, ProcessingError
 from xmodule.modulestore.django import modulestore
 from xmodule.modulestore.exceptions import ItemNotFoundError
@@ -728,12 +727,6 @@ def get_module_system_for_user(
     system.set('user_is_beta_tester', CourseBetaTesterRole(course_id).has_user(user))
     system.set('days_early_for_beta', descriptor.days_early_for_beta)
 
-    # make an ErrorBlock -- assuming that the descriptor's system is ok
-    if has_access(user, 'staff', descriptor.location, course_id):
-        system.error_descriptor_class = ErrorBlock
-    else:
-        system.error_descriptor_class = NonStaffErrorBlock
-
     return system, field_data
 
 

setup.py

@@ -24,7 +24,6 @@ XBLOCKS = [
     "library_content = xmodule.library_content_module:LibraryContentBlock",
     "library_sourced = xmodule.library_sourced_block:LibrarySourcedBlock",
     "lti = xmodule.lti_module:LTIBlock",
-    "nonstaff_error = xmodule.error_module:NonStaffErrorBlock",
     "poll_question = xmodule.poll_module:PollBlock",
     "problem = xmodule.capa_module:ProblemBlock",
     "randomize = xmodule.randomize_module:RandomizeBlock",

xmodule/error_module.py

@@ -227,20 +227,3 @@ class ErrorBlock(
             node.set(key, value)
 
         node.extend(list(exported_node))
-
-
-class NonStaffErrorBlock(ErrorBlock):  # pylint: disable=abstract-method
-    """
-    Block that gets shown to students when there has been an error while
-    loading or rendering other blocks.
-    """
-    def student_view(self, _context):
-        """
-        Return a fragment that contains the html for the student view.
-        """
-        fragment = Fragment(self.runtime.service(self, 'mako').render_template('module-error.html', {
-            'staff_access': False,
-            'data': '',
-            'error': '',
-        }))
-        return fragment

xmodule/tests/__init__.py

@@ -29,7 +29,6 @@ from xblock.fields import Reference, ReferenceList, ReferenceValueDict, ScopeIds
 from capa.xqueue_interface import XQueueService
 from xmodule.assetstore import AssetMetadata
 from xmodule.contentstore.django import contentstore
-from xmodule.error_module import ErrorBlock
 from xmodule.mako_module import MakoDescriptorSystem
 from xmodule.modulestore import ModuleStoreEnum
 from xmodule.modulestore.draft_and_published import ModuleStoreDraftAndPublished
@@ -167,7 +166,6 @@ def get_test_system(
             'replace_urls': replace_url_service
         },
         course_id=course_id,
-        error_descriptor_class=ErrorBlock,
         descriptor_runtime=descriptor_system,
     )
 

xmodule/tests/test_conditional.py

@@ -14,7 +14,7 @@ from xblock.field_data import DictFieldData
 from xblock.fields import ScopeIds
 
 from xmodule.conditional_module import ConditionalBlock
-from xmodule.error_module import NonStaffErrorBlock
+from xmodule.error_module import ErrorBlock
 from xmodule.modulestore.xml import CourseLocationManager, ImportSystem, XMLModuleStore
 from xmodule.tests import DATA_DIR, get_test_descriptor_system, get_test_system
 from xmodule.tests.xml import XModuleXmlImportTest
@@ -72,7 +72,7 @@ class ConditionalFactory:
                                             "problem", "SampleProblem", deprecated=True)
         if source_is_error_module:
             # Make an error descriptor and module
-            source_descriptor = NonStaffErrorBlock.from_xml(
+            source_descriptor = ErrorBlock.from_xml(
                 'some random xml data',
                 system,
                 id_generator=CourseLocationManager(source_location.course_key),

xmodule/tests/test_error_module.py

@@ -1,5 +1,5 @@
 """
-Tests for ErrorBlock and NonStaffErrorBlock
+Tests for ErrorBlock
 """
 
 
@@ -7,7 +7,7 @@ import unittest
 
 from opaque_keys.edx.locator import CourseLocator
 
-from xmodule.error_module import ErrorBlock, NonStaffErrorBlock
+from xmodule.error_module import ErrorBlock
 from xmodule.modulestore.xml import CourseLocationManager
 from xmodule.tests import get_test_system
 from xmodule.x_module import STUDENT_VIEW
@@ -42,28 +42,3 @@ class TestErrorBlock(SetupTestErrorBlock):
         context_repr = self.system.render(descriptor, STUDENT_VIEW).content
         assert self.error_msg in context_repr
         assert repr(self.valid_xml) in context_repr
-
-
-class TestNonStaffErrorBlock(SetupTestErrorBlock):
-    """
-    Tests for NonStaffErrorBlock.
-    """
-
-    def test_non_staff_error_block_create(self):
-        descriptor = NonStaffErrorBlock.from_xml(
-            self.valid_xml,
-            self.system,
-            CourseLocationManager(self.course_id)
-        )
-        assert isinstance(descriptor, NonStaffErrorBlock)
-
-    def test_from_xml_render(self):
-        descriptor = NonStaffErrorBlock.from_xml(
-            self.valid_xml,
-            self.system,
-            CourseLocationManager(self.course_id)
-        )
-        descriptor.xmodule_runtime = self.system
-        context_repr = self.system.render(descriptor, STUDENT_VIEW).content
-        assert self.error_msg not in context_repr
-        assert repr(self.valid_xml) not in context_repr

xmodule/x_module.py

@@ -1667,7 +1667,6 @@ class ModuleSystem(MetricsMixin, ConfigurableFragmentWrapper, ModuleSystemShim,
         descriptor_runtime,
         publish=None,
         course_id=None,
-        error_descriptor_class=None,
         **kwargs,
     ):
         """
@@ -1689,8 +1688,6 @@ class ModuleSystem(MetricsMixin, ConfigurableFragmentWrapper, ModuleSystemShim,
         course_id - the course_id containing this module
 
         publish(event) - A function that allows XModules to publish events (such as grade changes)
-
-        error_descriptor_class - The class to use to render XModules with errors
         """
 
         kwargs.setdefault('id_reader', getattr(descriptor_runtime, 'id_reader', OpaqueKeyReader()))
@@ -1704,7 +1701,6 @@ class ModuleSystem(MetricsMixin, ConfigurableFragmentWrapper, ModuleSystemShim,
 
         if publish:
             self.publish = publish
-        self.error_descriptor_class = error_descriptor_class
         self.xmodule_instance = None
 
         self.descriptor_runtime = descriptor_runtime